WO2024085574A1 - Separator for electrochemical device, and electrochemical device having same - Google Patents

Abstract

The present invention relates to a separator for an electrochemical device comprising a lithium manganese-based active material, the separator comprising: a porous polymer substrate; and a porous coating layer laminated on at least one side of the porous polymer substrate and comprising inorganic particles and a polymer binder, wherein the inorganic particles are made by a sulfonic acid group that is introduced onto the surface of a metal oxide or metal hydroxide, and at least a part of the sulfonic acid group is made by hydrogen cations that are replaced with lithium cations.

Description

Separator for electrochemical devices and electrochemical devices equipped with the same

The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2022-0133367 filed with the Korea Intellectual Property Office on October 17, 2022, the entire contents of which are included in the present invention.

The present invention relates to a separator for an electrochemical device and an electrochemical device comprising the same, and to a separator for minimizing capacity loss in an electrochemical device using a lithium-manganese-based positive electrode active material.

Electrochemical devices convert chemical energy into electrical energy using an electrochemical reaction. Recently, lithium secondary batteries, which have high energy density and voltage, long cycle life, and can be used in various fields, have been widely used.

A lithium secondary battery may include an electrode assembly made of a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and the electrode assembly may be manufactured by being stored in a case together with an electrolyte solution. The positive electrode can provide lithium ions, and the lithium ions can pass through a separator made of a porous material and move to the negative electrode. The negative electrode can be made of a carbon-based active material that has an electrochemical reaction potential close to that of lithium metal and allows insertion and desorption of lithium ions.

The positive electrode active material may contain lithium and various metal or transition metal elements. For example, nickel can improve the capacity of electrochemical devices, cobalt can improve the capacity and cycle stability of electrochemical devices, manganese can improve the stability of electrochemical devices, and aluminum can improve electrochemical devices. The output characteristics of the device can be improved. However, nickel has low thermal stability, and nickel and cobalt are expensive, so interest in lithium manganese-based positive electrode active materials containing manganese is increasing recently.

However, in electrochemical devices using a positive electrode active material containing manganese, manganese ions may be eluted from the positive electrode during the charging and discharging process. The eluted manganese ions may move to the cathode, precipitate as impurities including manganese on the surface of the cathode, and form a non-uniform film, causing capacity degradation of the electrochemical device.

Therefore, as a separator for use in an electrochemical device containing a lithium-manganese-based active material, it prevents deterioration of the cathode and the electrochemical device containing it by capturing manganese ions eluted from the anode and preventing them from moving to the cathode. Research is being conducted on separation membranes that can do this.

The purpose of the present invention is to provide a separator for use in an electrochemical device containing a lithium manganese-based active material, capable of adsorbing manganese ions eluted from an anode.

One aspect of the present invention includes a porous polymer substrate, a porous coating layer laminated on at least one side of the porous polymer substrate, and containing inorganic particles and a polymer binder, wherein the inorganic particles have a sulfonic acid group on the surface of the metal oxide or metal hydroxide. Provided is a separator for an electrochemical device containing a lithium manganese-based active material, wherein at least some of the sulfonic acid groups have hydrogen cations replaced with lithium cations.

The porous coating layer further includes second inorganic particles that are metal oxides or metal hydroxides included in the inorganic particles, and may include the inorganic particles and the second inorganic particles in a weight ratio of 80:20 to 70:30. there is.

The sulfonic acid group is selected from the group consisting of methane sulfonic acid, ethane sulfonic acid, trifluoromethane sulfonic acid, benzene sulfonic acid, p-toluene sulfonic acid, naphthalene sulfonic acid, phenylbenzimidazole sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid. There may be more than one.

The metal oxide or metal hydroxide is HfO ₂ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb2O ₅ , SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, Mg(OH) ₂ , NiO, CaO, ZnO, Zn ₂ It may be one or more selected from the group consisting of SnO ₄ , ZnSnO ₃ , ZnSn(OH) ₆ , ZrO ₂ , Y ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , AlOOH, Al(OH) ₃ and TiO ₂ .

The polymer binder is a non-aqueous polymer binder, and can bind the inorganic particles to each other to form an interstitial volume formed by the gap between the inorganic particles.

The non-aqueous polymer binder is polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-co-HFP), and N, N-bis[ It may be one or more selected from the group consisting of 3-(triethoxysilyl)propyl]urea.

The lithium manganese-based active material is Li _1+x Mn _2-x O ₄ (0≤x≤0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , LiNi _1-x Mn _x O ₂ (0.01≤x≤0.3 ), LiMn _2-x M _x O ₂ (M=Co, Ni, Fe, Cr, Zn or Ta, 0.01≤x≤0.1), Li ₂ Mn ₃ MO ₈ (M=Fe, Co, Ni, Cu or It may be one or more positive electrode active materials selected from the group consisting of Zn), LiNi _x Mn _2-x O ₄ (0<x<0.5), and LiMn ₂ O ₄ .

The porous coating layer may have a thickness of 1 to 6 ㎛.

The separator for electrochemical devices may have an adsorption rate of manganese ions eluted from the positive electrode containing the lithium manganese-based active material of 15 to 30%.

Another aspect of the present invention provides an electrochemical device including an anode, a cathode, and a separator disposed between the anode and the cathode, and the separator may be a separator for an electrochemical device according to an aspect of the present invention.

The electrochemical device may be a lithium secondary battery.

The separator for electrochemical devices according to the present invention introduces sulfonic acid groups on the surface of inorganic particles included in the porous coating layer, and replaces hydrogen cations contained in at least part of the sulfonic acid groups with lithium cations, thereby providing improved manganese ion adsorption capacity compared to the prior art. to provide.

Hereinafter, each configuration of the present invention will be described in more detail so that those skilled in the art can easily implement it. However, this is only an example, and the scope of rights of the present invention is determined by the following contents. Not limited.

As used herein, the term “comprising” is used to list materials, compositions, devices, and methods useful in the present invention and is not limited to the listed examples.

As used herein, “about” and “substantially” are used to mean a range or approximation of a number or degree, taking into account inherent manufacturing and material tolerances, and are provided as precise or absolute values to aid understanding of the present invention. is used to prevent infringers from unfairly using the mentioned disclosure.

As used herein, “electrochemical device” may mean a primary battery, secondary battery, super capacitor, etc.

As used herein, “particle size” means D50, which is the particle size corresponding to 50% of the cumulative distribution of particle numbers according to particle size, unless otherwise specified.

One embodiment of the present invention provides a separator for an electrochemical device including a porous polymer substrate and a porous coating layer containing inorganic particles and a polymer binder. The inorganic particles are those in which a sulfonic acid group is introduced to the surface of a metal oxide or metal hydroxide, and at least some of the sulfonic acid groups are hydrogen cations substituted with lithium cations, and the electrochemical device includes a lithium manganese-based active material.

The porous polymer substrate electrically insulates the positive and negative electrodes to prevent short circuits, while providing pores through which lithium ions can pass. The porous polymer substrate may be resistant to the electrolyte solution of the electrochemical device, which is an organic solvent. For example, the porous polymer substrate includes polyolefins such as polyethylene, polypropylene, and polybutene, polyvinyl chloride, polyethylene terephthalate, polycycloolefin, polyethersulfone, polyamide, polyimide, polyimideamide, polyaramid, It may include polymer resins such as polycycloolefin, nylon, polytetrafluoroethylene, and copolymers or mixtures thereof, but is not limited thereto. Preferably, the porous polymer substrate includes a polyolefin-based polymer, has excellent slurry applicability for forming a porous coating layer, and may be advantageous for manufacturing a thin-thickness separator.

The thickness of the porous polymer substrate may be 1 to 100 ㎛, preferably 1 to 30 ㎛, and more preferably 15 to 30 ㎛. The porous polymer substrate may include pores with an average diameter of 0.01 to 10 ㎛.

A slurry may be applied and dried on at least one surface of the porous polymer substrate to form a porous coating layer, which will be described later. The slurry may include inorganic particles, polymer binder, dispersion medium, etc. Before applying the slurry, surface treatment such as plasma treatment or corona discharge may be performed on the porous polymer substrate to improve impregnation with the electrolyte solution.

The separator for an electrochemical device may include the porous polymer substrate and a porous coating layer. The porous coating layer may be formed or laminated on at least one side of the porous polymer substrate, and preferably may be formed on both sides.

The porous coating layer may include inorganic particles to improve the mechanical properties and insulation properties of the porous polymer substrate and a polymer binder to improve adhesion between the electrode and the separator. The polymer binder provides adhesion between the electrode and the separator, and can also bond adjacent inorganic particles and maintain the bond. Inorganic particles can combine with adjacent inorganic particles to provide an interstitial volume, which is a void between the inorganic particles, and lithium ions can move through the interstitial volume.

The inorganic particles may form a uniform thickness of the porous coating layer and do not cause a redox reaction within the operating voltage range of the applied electrochemical device. Specifically, the inorganic particle may have a sulfonic acid group (HSO ₃ ) introduced to its surface, and may be a metal oxide or metal hydroxide in which a hydroxy group exists on the surface of the inorganic particle before the sulfonic acid group is introduced. Among these, the inorganic particles may be those having one or more of piezoelectricity and flame retardancy.

Inorganic particles with piezoelectricity refer to materials that are insulators at normal pressure but have the property of conducting electricity due to changes in their internal structure when a certain pressure is applied. The inorganic particles can exhibit high dielectric constant characteristics with a dielectric constant of 100 or more, and when a certain pressure is applied and stretched or compressed, an electric charge is generated, so that one side is positively charged and the other side is negatively charged, thereby generating a potential difference between both sides. It can have the function When an internal short circuit occurs between the anode and the cathode due to an external impact such as local crush or nail, the inorganic particles coated on the separator not only prevent the anode and the cathode from coming into direct contact, but also prevent the anode and the cathode from coming into direct contact due to the piezoelectricity of the inorganic particles. As a result, a potential difference occurs within the particle, which causes electron movement between the anode and the cathode, that is, a minute flow of current, which can gradually reduce the voltage of the electrochemical device and thereby improve safety.

For example, the piezoelectric inorganic particle may be HfO2 (hafnia), but is not limited thereto.

Inorganic particles with flame retardancy can add flame retardant properties to the separator or prevent the temperature inside the electrochemical device from rapidly rising.

For example, flame retardant inorganic particles include Sb ₂ O ₃ , Sb ₂ O ₄ , Sb2O ₅ , SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, Mg(OH) ₂ , NiO, CaO, ZnO, Zn ₂ SnO ₄ , ZnSnO ₃ , ZnSn(OH) ₆ , ZrO ₂ , Y ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , AlOOH, Al(OH) ₃ , TiO ₂ and mixtures thereof. It is not limited to this. Preferably, the inorganic particles may be AlOOH or Al(OH) ₃ .

The sulfonic acid group is one selected from the group consisting of methane sulfonic acid, ethane sulfonic acid, trifluoromethane sulfonic acid, benzene sulfonic acid, p-toluene sulfonic acid, naphthalene sulfonic acid, phenylbenzimidazole sulfonic acid, and 2-acrylamido-2-methylpropane sulfonic acid. It could be more than that.

As the hydrogen cation is released from the sulfonic acid group introduced into the inorganic particle, an attractive force acts between the electron-rich oxygen atom and the manganese ion, thereby giving the inorganic particle the ability to adsorb manganese ions.

At least some of the sulfonic acid groups may have hydrogen cations replaced with lithium cations. Substitution of the lithium cation can be accomplished by adding lithium hydroxide to the dispersion of the inorganic particles into which the sulfonic acid group is introduced and stirring. For example, hydrogen cations contained in 50 to 100% of the sulfonic acid groups present in the inorganic particles may be replaced with lithium cations, but the present invention is not limited to this. The lithium cation can be easily separated from the inorganic particles compared to the hydrogen cation, thereby improving the manganese ion adsorption capacity of the inorganic particles. In addition, lithium ions released from the inorganic particles improve lithium ion conductivity within the electrochemical device, thereby improving the performance of the electrochemical device.

The inorganic particles have sulfonic acid groups introduced to the surface of the inorganic particles, and at least some of the hydrogen cations of the sulfonic acid groups are replaced with lithium cations, and the average particle diameter may be 50 to 5000 nm, preferably 200 to 200 nm. It may be 1000 nm, more preferably 300 to 700 nm. If the average particle diameter of the inorganic particles is less than 50 nm, an additional polymer binder is required for bonding between the inorganic particles, which is disadvantageous in terms of electrical resistance. If the average particle diameter of the inorganic particles exceeds 5000 nm, the uniformity of the surface of the coating layer decreases, and the separator and electrode may be damaged during lamination by the protruding particles after coating, resulting in a short circuit. The specific surface area of the inorganic particles may be 5 to 10 m ² /g.

The porous coating layer may further include second inorganic particles that are metal oxides or metal hydroxides included in the inorganic particles. Preferably, the second inorganic particle may be a metal oxide or metal hydroxide contained in the inorganic particle, but may not have a sulfonic acid group introduced to its surface. For example, the porous coating layer includes AlOOH (boehmite) as the second inorganic particle, a sulfonic acid group is introduced to the surface of the boehmite as the inorganic particle, and at least some of the hydrogen cations of the sulfonic acid group are replaced with lithium cations. It can be included.

The porous coating layer includes both the inorganic particles and the second inorganic particles, and can improve the mechanical properties of the porous polymer substrate and provide manganese ion adsorption capacity. Specifically, the porous coating layer may include the inorganic particles and the second inorganic particles in a weight ratio of 80:20 to 70:30. If the first inorganic particles are included in excess compared to the above ratio, thermal shrinkage of the separator may occur due to a decrease in thermal stability. If the second inorganic particles are included in an excessive amount compared to the above ratio, the specific surface area of the porous coating layer decreases rapidly, and the adsorption capacity for manganese ions decreases at a rate greater than the decrease in the specific surface area. In a porous coating layer that satisfies the above ratio, the average specific surface area of all inorganic particles including the inorganic particles and the second inorganic particles may be 5.5 to 6.5 m ² /g.

The porous coating layer may include a non-aqueous polymer binder as a polymer binder. The weight average molecular weight of the non-aqueous polymer binder may be 10,000 to 10,000,000. For example, non-aqueous polymer binders include polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-co-HFP), and N,N- It may be one or more selected from the group consisting of bis[3-(triethoxysilyl)propyl]urea.

For example, the porous coating layer may include polyvinylidene fluoride-co-hexafluoropropylene as a non-aqueous polymer binder, and the non-aqueous polymer binder binds the inorganic particles to each other, creating a gap between the inorganic particles. An interstitial volume can be formed. When the porous coating layer further includes second inorganic particles, the non-aqueous polymer binder binds the inorganic particles to each other, the second inorganic particles to each other, and the inorganic particles and the second inorganic particles, thereby creating a gap between the inorganic particles. An interstitial volume can be formed.

The thickness of the porous coating layer may be 1 to 6 ㎛. If the thickness of the porous coating layer is less than 1 ㎛, a problem occurs in which impurities including manganese are precipitated at the cathode. Even if the thickness of the coating layer exceeds 6 μm, the manganese ion adsorption efficiency does not significantly increase. Preferably, the thickness of the porous coating layer may be 3 to 5 ㎛.

Both sides of the porous polymer substrate may be arranged to face a negative electrode and a positive electrode containing a lithium manganese-based active material, respectively. Preferably, a porous coating layer may be formed on both sides of the porous polymer substrate, and the porous coating layer may delay or reduce precipitation of impurities on the cathode surface of the electrochemical device. More preferably, the porous coating layer may include the same type of inorganic particles, and the porous coating layer may be formed by dip coating the porous polymer substrate with a slurry containing the inorganic particles.

The porous coating layer may further include a dispersant to further improve the dispersibility of the inorganic particles. The dispersant functions to maintain a uniform dispersion of inorganic particles within the polymer binder during slurry production. For example, the dispersant may be a cyano resin such as cyanoethyl pullulan or cyanoethyl cellulose. When the slurry includes a dispersant, the porous coating layer may include 5% by weight or less of the dispersant.

The slurry may contain inorganic particles and a polymer binder at a weight ratio of 90:10 to 10:90, preferably 80:20 to 20:80. If it is outside the above range, the movement of the polymer binder in the porous coating layer is hindered, making it impossible to secure sufficient adhesion between the electrode and the separator.

Another embodiment of the present invention provides an electrochemical device including an anode, a cathode, and a separator disposed between the anode and the cathode, wherein the separator is a separator for an electrochemical device according to the above-described embodiment. For example, the electrochemical device may be a lithium secondary battery including a positive electrode containing a lithium manganese-based positive electrode active material.

The positive electrode and the negative electrode may be formed by applying and drying an active material on at least one surface of each current collector. The current collector may be a material that has conductivity without causing chemical changes in the electrochemical device. For example, current collectors for positive electrodes include aluminum, nickel, titanium, fired carbon, and stainless steel; It may be a surface of aluminum or stainless steel treated with carbon, nickel, titanium, silver, etc., but is not limited to this. For example, current collectors for negative electrodes include copper, nickel, titanium, fired carbon, and stainless steel; It may be a surface of copper or stainless steel treated with carbon, nickel, titanium, silver, etc., but is not limited to this. The current collector may be in various forms, such as a thin metal plate, film, foil, net, porous material, or foam.

The lithium manganese-based positive electrode active material may not contain nickel and cobalt, or may contain only one of nickel and cobalt. For example, the lithium manganese-based positive electrode active material is Li _1+x Mn _2-x O ₄ (0≤x≤0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , LiNi _1-x Mn _x O ₂ (0.01≤ x≤0.3), LiMn _2-x M _x O ₂ (M=Co, Ni, Fe, Cr, Zn or Ta, 0.01≤x≤0.1), Li ₂ Mn ₃ MO ₈ (M=Fe, Co, Ni , Cu or Zn), LiNi _x Mn _2-x O ₄ (0<x<0.5), and LiMn ₂ O ₄ . Preferably, the lithium manganese-based positive electrode active material may be an LMO-based active material containing only lithium and manganese.

The negative electrode active material includes carbon such as non-graphitized carbon and graphitic carbon; Li _x Fe _{2 O 3} (0≤x≤1), Li _x WO ₂ (0≤x≤1 _{) , Sn} : Metal complex oxides such as Al, B, P, Si, elements of groups 1, 2, and 3 of the periodic table, halogen; 0<x≤1;1≤z≤8); lithium metal; lithium alloy; silicon-based alloy; tin-based alloy; SnO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂ O ₅ , GeO, GeO ₂ , Bi ₂ O ₃ , Bi ₂ O ₄ , metal oxides such as Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; It may include, but is not limited to, Li-Co-Ni based materials.

The electrochemical device may include a separator with the porous coating layer disposed on both sides, and the adsorption rate of manganese ions eluted from the positive electrode containing the lithium manganese-based active material may be 15 to 30%. Within the above range, precipitation of impurities containing manganese in the cathode may be delayed or reduced.

The electrochemical device can be manufactured by inserting the anode, cathode, separator, and electrolyte into a case or pouch and sealing it. The shape of the case or pouch is not limited. For example, the electrochemical device may be a cylindrical, prismatic, coin-shaped, or pouch-shaped lithium secondary battery.

The lithium secondary battery is packaged or modularized as a unit cell to be used in small devices such as computers, mobile phones, and power tools, and power tools that are powered by an electric motor; Electric vehicles, including Electric Vehicle (EV), Hybrid Electric Vehicle (HEV), Plug-in Hybrid Electric Vehicle (PHEV), etc.; Electric two-wheeled vehicles, including electric bicycles (E-bikes) and electric scooters (E-scooters); electric golf cart; It can be used in medium to large-sized devices such as power storage systems.

Below, the present invention will be described in more detail through specific examples and experimental examples. The following examples and experimental examples are intended to illustrate the present invention, and the present invention is not limited by the following examples and experimental examples.

Example 1

Preparation of slurry

5 g of boehmite (Nabaltec, D50 0.213 ㎛) was added to 200 mL of dichloromethane and dispersed using ultrasound for 20 minutes. 2 mL of chlorosulfonic acid was added to 50 mL of dichloromethane, and then added dropwise to the boehmite dispersion over 2 hours. After the addition was complete, the mixture was stirred at room temperature for 15 hours and centrifuged to obtain a solid. The solid was washed with dichloromethane more than five times and dried under vacuum at room temperature to obtain boehmite particles into which sulfonic acid groups were introduced. Boehmite particles with sulfonic acid groups introduced were added to a solution of 25 g of LiOH·H ₂ O dissolved in 500 mL of distilled water, and stirred for 12 hours. Inorganic particles were prepared by replacing hydrogen contained in some of the sulfonic acid groups with lithium.

100 mL of N-methyl pyrrolidone (NMP) was prepared as a non-aqueous dispersion medium at room temperature (25°C). A slurry for forming an organic/inorganic composite porous coating layer was prepared by dispersing polyvinylidene fluoride (Solvay) and dispersant (Miwon Corporation) as a polymer binder in the non-aqueous dispersion medium at a weight ratio of 10:1. 20 g of the inorganic particles were added to the slurry and stirred for 120 minutes to prepare a slurry in which the polymer binder and the inorganic particles were dispersed.

Preparation of porous polymer substrates

A polypropylene film (PP) with a thickness of approximately 9 ㎛ was used as a porous polymer substrate.

Manufacture of separation membrane

A polypropylene film was dip coated in the slurry and dried to form a porous coating layer with a thickness of 3 ㎛ on both sides of the film, thereby producing a separator with a total thickness of about 15 ㎛.

Example 2

A separator was prepared in the same manner as in Example 1, except that sulfonic acid groups were introduced to the surface of aluminum hydroxide as inorganic particles when preparing the slurry, and hydrogen contained in some of the sulfonic acid groups was replaced with lithium.

Example 3

In the same manner as Example 1, except that sulfonic acid groups were introduced as inorganic particles and lithium-substituted boehmite and unsurface-treated boehmite (second inorganic particles) were added in a weight ratio of 80:20 when preparing the slurry. A separation membrane was prepared.

Example 4

In the same manner as in Example 1, except that sulfonic acid groups were introduced as inorganic particles and lithium-substituted boehmite and unsurface-treated boehmite (second inorganic particles) were added at a weight ratio of 70:30 when preparing the slurry. A separation membrane was prepared.

Comparative Example 1

A separator was manufactured in the same manner as in Example 1, except that boehmite without surface treatment with inorganic particles was used when preparing the slurry.

Comparative Example 2

A separator was manufactured in the same manner as in Example 2, except that aluminum hydroxide without surface treatment with inorganic particles was used when preparing the slurry.

Comparative Example 3

In the same manner as in Example 1, except that sulfonic acid groups were introduced as inorganic particles and lithium-substituted boehmite and unsurface-treated boehmite (second inorganic particles) were added at a weight ratio of 60:40 when preparing the slurry. A separation membrane was prepared.

Experimental Example 1. Confirmation of physical properties of separation membrane

The thickness of the separators according to Examples 1 to 4 and Comparative Examples 1 to 3 and the porous coating layer of each separator was confirmed with a thickness gauge (Mitutoyo, VL-50S-B), and the inorganic particles contained in the porous coating layer in each separator were measured. The average specific surface area was measured and shown in Table 1 below.

	fabric	porous coating layer			Separator thickness (㎛)	Porous coating layer thickness (㎛/㎛)	Average specific surface area of inorganic particles in the porous coating layer ( m2 /g)
		Types of Mineral Particles	Inorganic particle surface treatment (+SO 3 -Li)	Inorganic particles: secondary inorganic particles weight ratio
Example 1	PP	AlOOH	○	-	15.1	3/3	5.71
Example 2	PP	Al(OH) 3	○	-	15.4	3/3	6.03
Example 3	PP	AlOOH	○	80:20	15.2	3/3	5.76
Example 4	PP	AlOOH	○	70:30	15.3	3/3	5.68
Comparative Example 1	PP	AlOOH	×		15.3	3/3	5.92
Comparative Example 2	PP	Al(OH) 3	×		15.2	3/3	6.72
Comparative Example 3	PP	AlOOH	○	60:40	15.4	3/3	5.72

Experimental Example 2. Confirmation of manganese ion adsorption performance of separation membrane

The separation membranes according to Examples 1 to 4 and Comparative Examples 1 to 3 were each completely immersed in a manganese sulfate solution (MnSO ₄ ) (initial Mn ²⁺ concentration of 3,400 ppm) and maintained for 24 hours, and then the membranes were recovered and dried. The dried separator was analyzed by EDS (JEOL SEM, 15kV) and is shown in Table 2 below.

In addition, after recovering the separator, the concentration of Mn ²⁺ ions remaining in the manganese sulfate solution was measured, and the Mn ²⁺ adsorption amount for each separator is shown in Table 2 below.

	EDS mapping results (Ratio of Mn 2+ ions, %)	Mn 2+ ion adsorption amount of separator (ppm)	Mn 2+ ion adsorption rate (%)
Example 1	1.58	548	16.11
Example 2	2.14	761	22.38
Example 3	1.37	385	11.32
Example 4	1.09	258	7.59
Comparative Example 1	0.27	0	0
Comparative Example 2	0.29	0	0
Comparative Example 3	0.77	0	0

Experimental Example 3. Confirmation of cycle characteristics in an electrochemical device containing lithium manganese-based active material

Lithium manganese composite oxide (LiMnO ₂ ): Conductive material (Denka black): Weigh the amount of binder (PVdF) so that the weight ratio is 95:2.5:2.5, then add it to N-methylpyrrolidone (NMP) and mix. A positive electrode active material slurry was prepared, and the positive electrode active material slurry was coated to a thickness of 200 μm on a 20 μm thick aluminum foil, followed by rolling and drying to prepare a positive electrode.

A Li metal plate with a thickness of 200 ㎛ was used as the cathode, and the anode and cathode were stacked with the separator of Example or Comparative Example in between, and then inserted into an aluminum pouch.

In the aluminum pouch, ethylene carbonate (EC)/ethylmethyl carbonate (EMC) is mixed in a weight ratio of 3/7, and as additives, 3 mol of vinylene carbonate (VC), 1.5 mol of propane sultone (PS), and ethylene sulfate are added. A cell was manufactured by injecting 1 g of an electrolyte solution containing 1 mol of (ESa) and 1 mol of the lithium salt LiPF ₆ and sealing the pouch.

The manufactured cell was charged and discharged once at 0.1 C in a voltage range of 3.0 V to 4.35 V in a 25°C chamber, and performance maintenance was confirmed by repeating 0.33 C charging and 0.33 C discharging 400 times. The performance maintenance rate was calculated as the ratio of the discharge capacity after repeating 400 cycles to the initial discharge capacity.

Additionally, the resistance was measured before and after the 400 cycles to confirm the resistance increase rate.

	Cell performance retention rate (%) after 400 cycles	Resistance increase rate (%) after 400 cycles
Example 1	85.7	7.12
Example 2	87.5	6.42
Example 3	80.4	23.40
Example 4	79.8	32.40
Comparative Example 1	70.4	36.81
Comparative Example 2	70.2	38.42
Comparative Example 3	71.4	39.12

Claims (10)

1. Porous polymer substrate; and

   It is laminated on at least one side of the porous polymer substrate and includes a porous coating layer containing inorganic particles and a polymer binder,

   The inorganic particles are,

   A separator for an electrochemical device containing a lithium manganese-based active material in which a sulfonic acid group is introduced to the surface of a metal oxide or metal hydroxide, and at least some of the sulfonic acid groups are hydrogen cations replaced with lithium cations.
2. According to paragraph 1,

   The porous coating layer is,

   It further includes second inorganic particles that are metal oxides or metal hydroxides included in the inorganic particles,

   A separator for an electrochemical device comprising the inorganic particles and the second inorganic particles in a weight ratio of 80:20 to 70:30.
3. According to paragraph 1,

   The sulfonic acid group,

   At least one selected from the group consisting of methane sulfonic acid, ethane sulfonic acid, trifluoromethane sulfonic acid, benzene sulfonic acid, p-toluene sulfonic acid, naphthalene sulfonic acid, phenylbenzimidazole sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid, Separator for chemical devices.
4. According to paragraph 1,

   The metal oxide or metal hydroxide is,

   HfO ₂ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb2O ₅ , SrTiO ₃ , SnO ₂ , CeO ₂ , MgO, Mg(OH) ₂ , NiO, CaO, ZnO, Zn ₂ SnO ₄ , ZnSnO ₃ , ZnSn(OH ) ₆ , ZrO ₂ , Y ₂ O ₃ , SiO ₂ , Al ₂ O ₃ , AlOOH, Al(OH) ₃ , and TiO ₂ , at least one selected from the group consisting of a separator for an electrochemical device.
5. According to paragraph 1,

   The polymer binder is,

   A separator for an electrochemical device, which is a non-aqueous polymer binder and bonds the inorganic particles to each other to form an interstitial volume formed by the gap between the inorganic particles.
6. According to clause 5,

   The non-aqueous polymer binder is,

   Polyethylene oxide (PEO), polyvinylidene fluoride (PVdF), polyvinylidene fluoride-co-hexafluoropropylene (PVdF-co-HFP), and N,N-bis[3-(triethoxysilyl) ) Profile] At least one separator for an electrochemical device selected from the group consisting of urea.
7. According to paragraph 1,

   The lithium manganese-based active material is,

   Li _1+x Mn _2-x O ₄ (0≤x≤0.33), LiMnO ₃ , LiMn ₂ O ₃ , LiMnO ₂ , LiNi _1-x Mn _x O ₂ (0.01≤x≤0.3), LiMn _2-x M _x O ₂ (M=Co, Ni, Fe, Cr, Zn or Ta, 0.01≤x≤0.1), Li ₂ Mn ₃ MO ₈ (M=Fe, Co, Ni, Cu or Zn), LiNi _x Mn ₂ A separator for an electrochemical device, which is at least one positive electrode active material selected from the group consisting of _-x O ₄ (0<x<0.5) and LiMn ₂ O ₄ .
8. According to paragraph 1,

   The porous coating layer is,

   A separator for electrochemical devices with a thickness of 1 to 6 ㎛.
9. According to paragraph 1,

   A separator for an electrochemical device, wherein the adsorption rate of manganese ions eluted from the positive electrode containing the lithium manganese-based active material is 15 to 30%.
10. An electrochemical device comprising an anode, a cathode, and a separator disposed between the anode and the cathode,

    The separator is a separator for an electrochemical device according to any one of claims 1 to 9.